Drying oils



Patented Feb. 21, 1950 DRYING OILS Peter Kass, Wilmington, Del, andJoseph Nichols, New York. N. Y., alslgnors to Interc hemicalCorporation, New York. N. 1., a corporation of Ohio No Drawing.Application May 8, 194

Serial No. 748,860

Claims. (Cl. 260-398) This invention relates to the modification oidrying oils by treating the oils with acetic anhydride to improve theirdrying qualities. The invention is particularlyconcerned vwith thetreatment of mixtures of tung oil with one or more other drying oils byrefluxing the mixture of oils with acetic anhydrideand then removing theacetic anhydride.

Several methods for improving the drying properties of unsaturated fattyacid glyceride oils have been proposed. Among such proposed processes isone which consists in heating the oil to be modified with an oxidizingagent such as peroxide or an inorganic chromate or permanganate. Aprocess which has been proposed for treating oiticia oil and po-yoak oilconsists in heating the oil withacetic anhydride at temperaturesof 200to 230 C. This treatment results in an increase in the drying rate ofthe oil.

In the copending application of Joseph Nichols, Serial Number 748,859,filed May 8, 1947, a process for treating tung oil with acetic anhydrideis disclosed and claimed. It has now been discovered that when tung oil,which has been treated with acetic anhydride according to the procedurein the above application, is admixed with other drying oils commonlyused in preparation of varnishes, printing inks, and the like, thebeneficial effect of the acetic 'anhydride treatment of the tung oil islost; the mixture of the treated tung oil with other untreated oilsdried in no way different from a mixture of identical proportions ofuntreated tung oil and other untreated oils. We have now discovered thatmixtures of tung oils and other oils will dry in the expected improvedmanner only ii! the entire mixture has been treated with aceticanhydride. This treatment with acetic anhydride may be carried out onthe individual oils before mixing or it may be carried out on themixture of oils,

subsequent to mixing of the oils, The preferred procedure for carryingout our invention consists in refluxing the desired mixture of oils with5 to 30 per cent of their weight of acetic anhydride at from about 160to 180 C. for from about 1 to 4 hours and then removing the aceticanhydride. It is obvious that the same result is accomplished bytreating the individual oils separately with acetic anhydride' and thenmixing them.

Our process is applicable to any mixture of tune oil with other oils,either raw or bodied, such as linseed oil. dehydrated castor oil and thelike. The particular ratio of tune oil to be used with other drying oilsis not critical. Such ratio-will fer to remove the acetic anhydrideunder nonoxidizing conditions, we may also remove it by any other usualmeans, as by mere distillation or by washing the oil with water.Practically all of Y the acetic anhydride may be recovered.

Mixtures of tung oil with other drying oils which have been treated withacetic anhydride according to the hereinabove described process havephysical properties such as viscosity, re-

' iractive index, color, etc., similar to the untreated oils; however,the treated oils dry to a tack-free film in only a fraction of the timerequired for the untreated oils to dry to the same degree under similarconditions. Also, the mixtures of tung oil with other dryin treatedaccording to the process of our invention, tend to dry faster as theamount of tung oil in the mixture is increased. This is shown by thedata contained in Table I.

Table 1 Composition of Mixture Drying Time 'lrcate i 'lreated ing 0nsecd o per cent by per cent by 0 weight weight 70 2 hrs 5c 1 hrs.- 4;:min. 30 50 min 1 min. 10 35 The drying times were determined byspreading a film oi the oil on a glass microscope slide and noting thetime required for the film to dry to a non-tacky state at the particulartemperatures stated. Under similar conditions, mixtures of tung oil withdehydrated castor oil and soybean oil give similar results. Syntheticdrying oils, for instance oils made by esterifying pentaerythritol withlinseed fatty acids,- also may be used in our process.

3 Table II shows the comparative drying im of several mixtures oftreated tung oil with treated dehydrated caster oil and with untreateddehydrated castor oil.

' Table II Composition oi Mixture,

per cent by weight I a Drying time t d t ted b g s c to tea a on 32%ated deh ydrated was on cas t or oil castor oil 90 10 1% hrs.- 90 10 35min. 70 30 2% hrs. 70 30 1% hrs. 50 50 4 hrs. 50 60 2 hrs.

Table III shows the comparative drying times of several mixtures oftreated tung oil with untreated soya oil and treated soya oil.

Table III Composition of Mixtures, per cent by weight Dryin in air at aout treated untreated treated 25 C. tung oil soya oil soya oil 80 20 3hrs.

80 20 40 min.

50 60 5 hrs.

50 50 2% hrs.

In addition to drying faster at room temperature the acetic anhydridetreated oils also dry faster under other conditions as at a bakingtemperature of 110 C. or under ultraviolet light.

The improved drying oils prepared according to the process of the hereindisclosed inventions are useful in the formulation of rapid dryingcoating compositions in the same general manvents, coloring substances,plasticizers, resins, and the like.

We claim:

other 1. A process for improving the drying qualities of mixtures oftung oil with other drying oils which comprises refluxing the mixturewith acetic anhydride at to C. and removing the acetic anhydride.

2. A process for improving the drying qualities of mixtures of tung oilwith other drying oils which comprises refluxing the mixture with aceticanhydride at 160 to 180 C. and removing the anhydride undernon-oxidizing conditions.

3. A process for improving the drying qualities of mixtures of tung oilwith other drying oils which comprises refluxing the mixture with aceticanhydride at 160 to 180 C. and removing the acetic anhydride underreduced pressure.

4. A process for improving the drying qualities REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Nessler et al Aug. 5, 1947 Number 4 neras other drying oils. 1. e. by mixing with so

1. A PROCESS FOR IMPROVING THE DRYING QUALITIES OF MIXTURES OF TUNG OILWITH OTHER DRYING OILS WHICH COMPRISES REFLUXING THE MIXTURE WITH ACETICANHYDRIDE AT 160* TO 180*C. AND REMOVING THE ACETIC ANHYDRIDE.